In 1995, the United States Federal Aviation Administration (FAA) made a wealth of minute-by-minute radar-based flight tracking information available for distribution to the public with the creation of the Aircraft Situation Display to Industry (ASDI) service. Through this service, flight tracking data is made available to several vendors from a single source. The ASDI information includes the location, altitude, airspeed, origin, destination, estimated time of arrival and tail number or designated identifier of air carrier and general aviation aircraft operating on at least the corresponding IFR flight plans within U.S. airspace. General aviation VFR flights that include air traffic control flight following are often included.
In addition, other sources of flight tracking information are available, including next-generation automatic dependent surveillance broadcast (ADS-B) information, which may be utilized independently or in combination with the ASDI data to provide the requested flight tracking information.
ADS-B provides real-time position information that is, in many cases, more accurate than the information available with traditional radar-based systems. ADS-B uses GPS signals along with aircraft avionics to transmit an aircraft's location from an on-board transceiver to permanent receivers located on the ground. The ground receivers then transmit that information to air traffic controllers, cockpit displays of other aircraft equipped with ADS-B avionics, and the like. An aircraft equipped with ADS-B also periodically broadcasts other relevant information such as the aircraft's identification, altitude, and velocity. Currently, this information is broadcast approximately every second.
The on-board portion of the ADS-B system relies on two avionics components: (1) a high-integrity GPS navigation source and (2) a datalink (ADS-B unit). There are several types of certified ADS-B data links, but the most common ones operate at 1090 MHz. It is expected that most, if not all, commercial aircraft will be equipped with ADS-B equipment by 2020.
A private corporation was awarded a contract in August of 2007 to build, install and maintain a nationwide network of ADS-B ground receivers. Typically, these ground receivers are located at, near, or are in direct communication with airports, as the system has an effective operating range of roughly 100 to 150 miles. It is expected that ground receivers sufficient to provide coverage for the entire airspace over the continental U.S. will be in place by 2013.
The wealth of information collected by the ADS-B service, and other information collection systems like it, is attractive to users of ADSI data, such as those who provide near real-time flight tracking information. However, given that the data includes a number of data points (i.e. location, airspeed, altitude) regarding each aircraft within its range, and that that data is received every second, the sheer volume of the data is difficult to manage. Furthermore, given that this volume of data is available at each and every ground receiver location, the amount of data available nationwide is tremendous. As a result, the task of transmitting and processing this information for subsequent use, such as for presentation to users, is an extremely difficult one. A brute force approach to the collection of this massive amount of data on a continuous basis would likely be cost prohibitive from a bandwidth and processing perspective. Some efforts to address this problem use a simple sampling, in that only every tenth or every twentieth data point collected are forwarded for later use. Even if data known compression techniques were to be used, the amount of data would still be overwhelming, and the compressions algorithms would require ample processing power at each end. Accordingly, the present invention solves a number of these problems as well as other problems present in the aviation information industry, as are illustrated in the descriptions that follow.